Multi-drug resistance (MDR) means that the tumor cells have cross-resistance to various anti-cancer drugs with different chemical structure, function and mechanism. Clinical study shows that some solid tumors such as colonic cancer, renal cancer, hepatocarcinoma, non-small cell lung cancer, glioma, kaposis sarcoma, and prostate cancer are generally drug resistant, even probably at the time when they are just been diagnosed, thus belonging to intrinsic MDR. In these tumor cells, there are usually various resistance mechanisms concurrently provoking a broad resistance to chemotherapeutic drugs. Whilst, some tumors such as acute myeloid leukemia, acute lymphocytic leukemia, multiple myeloma, lymphoma, mammary cancer, and ovary cancer are generally sensitive to chemotherapeutic drugs at the initial treatment stage but become drug-resistant gradually during the treatment, especially during the treatment of recurrence when the drug-resistance significantly increases. This type of drug-resistance is called acquired MDR. The therapeutic effect would fall notably after the establishment of the drug-resistance. MDR results in poor therapeutic effect, bad prognosis and easy tumor recurrence and metastasis of the conventional chemotherapies. About 90% of the dead cases in tumor patients are associated with the intrinsic or acquired drug-resistance.
The mechanisms of the occurrence of MDR have been studied widely. Seen as a whole, MDR is co-regulated by multiple factors and multiple mechanisms, mainly including the efflux of chemotherapeutic drugs by ABC transfer proteins, the enhanced expression of anti-apoptosis proteins, the alteration of metabolic pathway and regulating mode, and the enhancement of detoxification system.
Therefore, a chemotherapeutic sensitizer with notable effect is urgently needed in the prior art.